Process for producing preformed wire from silicon carbide fiber-reinforced aluminum

ABSTRACT

A process for producing a preformed wire from silicon carbide fiber-reinforced aluminum, which comprises silicon dipping a bundle of silicon carbide fibers for a period of 60 seconds or shorter in a melt of a eutectic alloy composed of aluminum and 5.0 to 7.0 wt. % of nickel added thereto which melt is kept at or below the liquidus temperature of the melting point thereof plus 50° to impregnate said fiber bundle with said alloy.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for producing a preformedwire from silicon carbide fiber-reinforced aluminum as an intermediatematerial of FRM, and particularly to a process for producing a preformedwire of the kind as described above which is prevented fromdeteriorating in strength at high temperatures. The concept of apreformed wire as defined in the present invention comprehends preformedsheet and tape as well.

2. Prior Art

Composite materials composed of a metal, such as aluminum, and a fibrousmaterial, such as a silicon carbide fiber, impregnated therewith haveheretofore been promising and expected as materials widely applicable tovehicles, airplanes, rockets, spacecraft, and the like by virtue oftheir merits respectively attributable to the metal and the fibrousmaterial, such as toughness, lightness, and flexibility.

Various methods of producing such a metal-fiber composite material havebeen proposed. One example of them is a method comprising blowing finemetallic particles or a metallic vapor against a bundle of fibers byplasma jetting, metallikon, or vacuum evaporation to adhere a metal tothe surfaces of the fibers to thereby produce a metal-fiber compositematerial or precursor thereof. However, this method is defective in thatno composite material having satisfactory strength and elasticity can beobtained because fine metallic particles or a metallic vapor is sostraight forward blown against a bundle of fibers that the metal cannotpenetrate well into the inside of the fiber bundle.

Another proposed method comprises dipping a bundle of fibers in a moltenmetal bath while ultrasonically vibrating the molten metal bath to causethe molten metal to penetrate into the inside of the fiber bundle. Inthis case, although a bundle of fibers is opened by ultrasonic vibrationto expel air present inside the fiber bundle so that the metal isallowed to penetrate well into the inside of the fiber bundle, thefibers are fixed in a disorderly opened state due to the vibration sothat a difficulty is encountered in imparting desired strength andelasticity to the resulting metal-fiber composite material.

A method disclosed in Japanese Patent Laid-Open No. 34,167/1986 wasproposed with a view to solving the above-mentioned problems. Thismethod comprises spreading and arranging in order a bundle of siliconcarbide fibers, and passing the bundle of silicon carbide fibers througha melt of a metal such as aluminum while ultrasonically vibrating themelt. However, this method is insufficient to prevent deterioration instrength of the resulting composite material at high temperatures.Namely, in the production of a preformed wire from silicon carbidefiber-reinforced aluminum when fibers are impregnated with an aluminummelt at a high temperature for a long period of time, an interfacialreaction occurs in the surface layers of the fibers to deteriorate thesame. Some improvement can be attained against the deterioration offibers when the melt is ultrasonically vibrated to shorten the time ofimpregnation for the purpose of preventing the deterioration. However,the improvement is yet insufficient. Moreover, the strengthcharacteristics of the resulting composite material at high temperaturescannot be improved.

The present invention has been made in view of the above-mentioned stateof art. An object of the present invention is to provide a process forproducing a preformed wire from silicon carbide fiber-reinforcedaluminum which is prevented from deteriorating in strength at hightemperatures by causing aluminum to penetrate well in between the fibersat a low temperature to effect impregnation without deterioration of thefibers.

SUMMARY OF THE INVENTION

It has been found that the above-mentioned object of the presentinvention can be attained by treating a bundle of silicon carbide fibersin a melt of a eutectic alloy composed of aluminum and 5.0 to 7.0 wt. %of nickel added thereto which melt is kept at a specified temperature,and that such a treatment enables not only the impregnation of fiberswith an alloy to be effected at a low temperature, which serves tosuppress the deterioration of the fibers, but also the internal defectof a preform being produced thereby to be suppressed by virtue of anarrow temperature range for solidification of the alloy to therebyprovide a high level of strength of the preform at high temperatures.

Namely, the present invention provides a process for producing apreformed wire from silicon carbide fiber-reinforced aluminum,characterized by spreading and arranging in order a bundle of siliconcarbide fibers and continuously dipping the fiber bundle for a period of60 seconds or shorter in a melt of a eutectic alloy composed of aluminumand 5.0 to 7.0 wt. % of nickel added thereto which melt is kept at orbelow the liquidus temperature of the melting point thereof plus 50° C.to impregnate the fiber bundle with the alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic process diagram of one embodiment of the processfor producing a preformed wire according to the present invention, and

FIG. 2 is a graph showing the tensile strength versus temperaturerelationships in Examples 1-2 and Comparative Example.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail while referring tothe attached drawings.

In FIG. 1, a bundle of silicon carbide fibers 2 spreaded and arranged inorder with a fiber bundle arrangement unit 1 is introduced via guiderolls 3a and 3b into a molten alloy bath 5 filled with a molten eutecticalloy 4 composed of aluminum and 5.0 to 7.0 wt. % of nickel addedthereto to impregnate the fiber bundle with the eutectic alloy.

It is desirable that the molten alloy 4 be vibrated with an ultrasonicvibrator unit 6. The ultrasonic vibration is effective in promoting thepenetration of the eutectic alloy into the silicon carbide fiber bundle.

It is necessary to keep the temperature of the molten alloy bath 5 at orbelow the liquidus temperature of the melting point of the eutecticalloy plus 50° C. It is required that the time of dipping the siliconcarbide fiber bundle 2 in the bath should be 60 seconds or shorter. Whenthe bath temperature of the molten alloy 4 exceeds the liquidustemperature of the melting point plus 50° C. and/or when the time ofdipping the silicon carbide fiber bundle 2 exceeds 60 seconds, theinterfacial reaction of the surface layers of the fibers drasticallyproceeds to deteriorate the fibers unfavorably.

The silicon carbide fiber bundle 2 thus impregnated in an orderlyarranged state with the eutectic alloy has the eutectic alloy which haswell penetrated in between the fibers to have only few voids in thebundle and forming an alloy phase comprised of 0.01 to 1.0 μ fibrouseutectic phases or lamellar eutectic phases.

The silicon carbide fiber bundle 2 is then continuously drawn into adesired shape via guide rolls 3c and 3d and through a slit 7 or a diewhile squeezing a surplus of the alloy to form a fiber- and eutecticphase-reinforced preformed wire with a predetermined fiber content byvolume, which is then, for example, wound around a wind-up unit 8.Although description has been made of the preformed wire in the presentspecification, the concept of a preformed wire as defined in the presentinvention comprehends preformed sheet and tape as describedhereinbefore.

As described above, the process of the present invention is effective inthat fibers can be impregnated with a eutectic aluminum alloy even at alow temperature without deterioration of the fibers to form a preformedwire of silicon carbide fiber-reinforced aluminum which undergoes nodeterioration in strength even at high temperatures and has no internaldefect therein in virtue of a narrow temperature range forsolidification of the aluminum alloy.

DESCRIPTION OF THE PREFERED EMBODIMENTS

The present invention will now be specifically illustrated on the basisof Examples and Comparative Example.

Example 1

A melt of an aluminum--5.7 wt. % nickel eutectic alloy was kept at atemperature of 670° C., higher by 30° C. than the melting point thereof.A fiber bundle of 250 silicon carbide monofilaments of 13 μ in diameterwas arranged in order, opened, and continuously dipped in the melt for10 seconds to impregnate the bundle with the aluminum-nickel eutecticalloy to thereby produce a preforme wire of 0.3 mmφ. FIG. 2 shows thetensile strengths of this wire at various temperatures.

Example 2

A preformed wire was produced in substantially the same manner as thatof Example 1 except that continuous dipping of a fiber bundle of siliconcarbide monifilaments was conducted for 1 second with ultrasonicvibration of a reasonance frequency of 20 kHz. FIG. 2 also shows thetensile strengths of this wire at various temperatures.

Comparative Example

A preformed wire was produced in substantially the same manner as thatof example 2 except that pure aluminum was kept as a melt at atemperature of 690° C., higher by 30° C. than the melting point thereof.FIG. 2 also shows the tensile strengths of this wire at varioustemperatures.

As shown in FIG. 2, the preformed wire of Comparative Example showed atensile strength at 450° C. representing a decrease to about 90% of thatat ordinary temperatures, while the tensile strengths at 450° C. of thepreformed wires of Examples 1 and 2 were respectively kept at levelssubstantially equal to those at ordinary temperatures.

What is claimed is:
 1. A process for producing a preformed wire fromsilicon carbide fiber-reinforced aluminum, characterized by spreadingand arranging in order a bundle of silicon carbide fibers andcontinuously dipping said fiber bundle for a period of 60 seconds orshorter in a melt of a eutectic alloy composed of aluminum and 5.0 to7.0 wt. % of nickel added thereto which melt is kept at or below theliquidus temperature of the melting point thereof plus 50° C. toimpregnate said fiber bundle with said alloy.
 2. A process as claimed inclaim 1, wherein said impregnation of said fiber bundle with said alloyis effected while ultrasonically vibrating said melt.